Advanced lithographic techniques such as 193 nm immersion lithography have been developed to achieve high quality and smaller feature sizes in microlithography processes, for purposes of forming ever-smaller logic and memory transistors. It is important to achieve both smaller critical dimension (CD) in the imaged photoresist used in the microlithography process, and for the photoresists to provide both the lowest line edge roughness (LER) and line width roughness (LWR), while still retaining good process control tolerances such as high exposure latitude (EL) and a wide depth of focus (DOF).
To meet the challenges for resist materials raised by high resolution lithography, photoacid generators (PAGs) have been made which are soluble in aqueous developers and have low absorbance. A variety of photoacid generators (PAGs) used for formulating photoresists are found in prior art, such as those having fluorine-containing cations as disclosed in U.S. Patent Application Publication No. 2005/0079441 A1. However, a need remains for photoresist compositions including PAGs having controlled solubility characteristics in both aqueous and non-aqueous solvents, as well as diffusion control and attendant properties such as resist profile.